Resolution and contrast of existing techniques for spatial image acquisition, particularly for microscopy of living organisms, have been significantly improved in recent years. Widespread techniques with high resolution, such as the confocal microscopy described in printed publication DE 43 26 473, are based on the spatially resolved acquisition of an overlap of illumination volume and acquisition volume. The volume of the overlap determines the resolution. Alternative processes, such as optical coherence microscopy (OCM) and optical coherence tomography (OCT), determine the axial depth interferometrically by means of light of short coherence length. More recent techniques, such as the optical projection tomography (OPT) described in Science 296, 541 (2002) by J. Sharpe et al., transirradiate the specimen volume at a plurality of different angles and attain a dependent resolution from 1 μm to 5 μm.
Document WO 2004/020997 A1 describes an apparatus with a rotatable object stage for rotating the specimen to be imaged. A main detector acquires only light that leaves the specimen parallel to the light-incidence direction. In further embodiments, a main detector and a plurality of auxiliary detectors have been arranged in a one-dimensional or two-dimensional matrix in the beam direction downstream of the specimen with a view to angle-resolved acquisition of light, whereby light deflected from the specimen is acquired by the auxiliary detectors.
Document US 2007/0109633 A1 describes a microscope that transilluminates a plane in the specimen volume with a set of parallel beams of light. The illumination plane that is formed in this manner is acquired in its two dimensions by a CCD camera at a right angle to the illumination plane in spatially resolved manner. In a further embodiment, two illumination planes are irradiated. By superimposition of two coherent illumination planes, the intensity distribution in the superimposed illumination plane is structured by interference patterns with a view to improving the positional resolution in the illumination plane. With a view to spatial image acquisition, the illumination plane and the specimen are moved towards one another. A further embodiment illuminates the specimen substantially one-dimensionally and acquires the specimen in this dimension in spatially resolved manner with a linearly increased number of pixels.
Document US 2007/0274580 A1 describes a technique for optical tomography. Fluorescent proteins in a specimen are excited by incident light. The exciting light in the specimen and the fluorescent light are diffuse. A spatially resolved image is acquired and processed.
The science publication “Forward and Inverse Calculations for 3-D Frequency-Domain Diffuse Optical Tomography”, B. W. Pogue et al., SPIE Vol. 2389, pages 328-339, describes a process of diffusive optical tomography (DOT). For a simulation of the process it is assumed that a plurality of detectors have been arranged around an object on a circle.
The known techniques for spatial image acquisition can, by reason of a radiation intensity acting on the specimen, distort the image acquisition, change the specimen in uncontrolled manner or, particularly in the case of in vivo microscopy, destroy the specimen. Also, the technical effort in order with the prior techniques to diminish the radiation intensity with comparable image results may rise considerably.